In a node in a wireless communication system, there is sometimes a need for re-using an antenna arrangement designed for a first cellular system in a second cellular system. However, the second cellular system may have requirements on the antenna arrangement which is different from the requirements of the first cellular system.
One example of such a situation is if an SCDMA (Spatial Code Division Multiple Access) system, a first cellular system, is to be migrated to a 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) system, a second cellular system. The SCDMA system may have been deployed with array antennas that have more antenna ports than is needed for the transmission modes used in LTE. A possible way to reuse the antennas in such a scenario is to split the sectors in the SCDMA system into two sectors for the LTE system. The number of antenna ports per sector in the LTE system is then half the number of antenna ports per sector in the SCDMA system.
Generally, a straightforward solution to this problem is to replace existing antennas with new antennas that are designed for the second cellular system. However, replacing antennas in an entire system is a very costly operation, making reuse of existing antennas an attractive alternative.
There is thus a desire to reuse an existing antenna arrangement which is to be used in a second cellular system but has been designed for a first cellular system, where the second cellular system has requirements on the antenna arrangement which is different from the requirements of the first cellular system.